Impact valve for metal-cutting machines



P 9 J. Am'zsnsou 2,634,756

IMPACT VALi'E FOR METAL CUTTII IG. MACHINES Filed Dec. 11, 1950 Patented Apr. 14, 1953 UNITED STATES PATENT OFFICE IlVIPACT VALVE FOR METAL-CUTTING MACHINES James Anderson, Newton Mearns, Scotland 3 Claims.

This invention has reference to a valve for metal cutting machines and particularly to metal boring, facing, turning and like machines wherein the job being operated on is rotated while a cutting tool operates thereon while being fed relative to the job by means of an hydraulic feed.

In boring, facing and turning certain metals, e. g. steel, the metal cut away, commonly referred to as chip and when in bulk referred to as swarf, is in the form of a thin ribbon or spiral. The chip in addition to constituting a danger to the machine operator and to those in the vicinity must be rapidly disposed of as otherwise it will clog the machine and hamper production.

The present invention has for its object to provide improvements in such machines whereby the aforesaid danger and the hampering of production will be surmounted.

According to the present invention in a machine of the type set forth the hydraulic feed system is provided with a relief valve and means by which said valve is intermittently momentarily opened so that the feed is intermittently momentarily checked whereby the chip is weakened at or cut off at predetermined intervals.

The invention further consists in a machine as set forth in the preceding paragraph wherein the valve is intermittently momentarily opened by the kinetic energy of a member to which an impulse is intermittently imparted by gravity or otherwise. Means may be provided by which the kinetic energy of said member can be varied to control the opening of the valve and, therefore, the extent to which the chip is weakened at predetermined intervals.

The invention will now be described with reference to the annexed drawing which shows diagrammatically one embodiment thereof.

In the drawings a designates an hydraulic cylinder and b a piston working therein. This piston and cylinder assembly constitutes the hydraulic feed of a metal boring, facing, turning and like machine, the cutting tool being fed by the hydraulically loaded piston towards the job being operated on, as the latter is being rotated, under pressure supplied to the cylinder through the pipe line 0.

Connected to this pipe line is a valve body d in which is fitted a mitre valve e normally held on its seat 1 by a helical compression spring g and by the pressure of liquid supplied thereto from the pipe line 0. Said spring bears on the mitre valve and also on a spring carrier h screwed into the valve body. The spindle i of the mitre valve is extended through and projects beyond the valve body. Surrounding the spindle is a cylindrical chamber 7' which communicates with an outlet pipe line is.

Arranged to co-operate with the outer end of the valve spindle is a lever Z pivoted at m to lugs n carried by the valve body. The lever on one side of its pivot is in the form of a screw threaded spindle 0 on which is threaded a heavy Weight 11.

The other end of the lever co-operates with a rotary cam q which is rotated through any suitable gearing by a motor which may be the motor which drives the machine spindle by which is rotated the job to be operated on.

Said cam is so shaped that when rotated it intermittently turns said lever I about its pivot and against the action of the weight 1) and then releases said lever so that it descends under the action of gravity to strike the valve spindle i and thereby momentarily open the valve. In the drawing the cam, which is being rotated in the direction indicated by the arrow, is on the point of releasing the lever 12. The opening of the valve is not affected by the weight 11 but is due to the kinetic energy of the falling weight so that immediately the valve is opened it closes again under the action of its spring. This momentary opening of the valve permits a minute quantity of the pressure fluid in the feed system to escape and this in turn checks or interrupts the feed of the tool towards the work suflicient to lessen the depth of out.

When the machine is in operation the pivoted lever l with weight is intermittently raised and released so that it falls by gravity. The kinetic energy of the falling lever and weight is imparted to the valve spindle 2' so that the valve e is intermittently and momentarily opened to permit a very small amount of the hydraulic fluid to escape past the valve at each opening movement. The feed of the tool with respect to the job is in consequence momentarily slowed down or interrupted at each escapement. Consequently the chip, as it is formed, is weakened, that is thinner, at regularly spaced distances apart.

If the interruption of the feed is sufficient th chip may be cut through at regular intervals. This would mean that the tool would require to cut into the metal after each length of chip has been cut off. It is preferred, however, that the chip should be only weakened at intervals. It is then found that the chip instead of being delivered in long continuous spirals or ribbons, will break off in short lengths under the action of the rotating chuck or tool contacting therewith. Should, however, the chip not be sumciently weakened to ensure that it will be easily broken it can be readily bent back on itself at the points of weakness so that it can be easily formed into a bundle for easy disposal.

The intervals at which the valve is opened may be varied by adjusting the means by which the cam q is rotated, and the duration of opening of the valve, and, therefore, the degree to which the feed is checked or interrupted can be controlled by adjusting the weight 2) on the lever. This in turn adjusts the kinetic energy imparted to open the valve.

In lieu of the lever falling under the action of gravity it may be spring loaded. In such case the cam will intermittently retract and release the spring. But the spring must be such that it will not open the valve by itself, this must be done by the kinetic energy so that the valve will close immediately.

According to a modification the valve may be operated by means of a reciprocating weight which is raised by mechanical, electrical, hydraulic or pneumatic means and thereafter permitted to drop to operate the valve.

What I claim is:

1. In the hydraulic feed system of a machine of the type set forth, a relief valve, a loaded relief valve operating member, the loading being insufficient to open the valve, and means to intermittently retract and then release said memher so that it strikes the relief valve and by its kinetic energy momentarily opens the valve so that the feed is intermittently checked.

2. In the hydraulic feed system of a machine of the type set forth, a relief valve, a pivoted relief valve operating member, means by which said member is loaded, the loading being insufficient to open the relief valve, and a cam to intermittently retract and release said member so that it strikes the relief valve and by its kinetic energy momentarily opens the valve to momentarily check the feed.

3. In the hydraulic feed system of a machine of the type set forth'a relief valve and means for intermittently and momentarily opening the said valve as claimed in claim 1 wherein the valve operating member is provided with means to vary its loading so that the momentary opening of the valve and therefore the extent to which the feed is checked, can be varied.

JAMES ANDERSON.-

References Cited in the file of this patent UNITED STATES PATENTS Number 

